Are they a symbol of Big Brother, a good design practice or something in between? Here's a real world example of clustering multiple surveillance cameras on a single pole:
They look a little like leaves on a CCTV tree. While this does happen, it is uncommon.
Benefits of CCTV Camera Clusters
We see a few benefits of this approach:
Lower installation cost: Instead of running cabling to 4 different locations, just a single run is required.
Dedicated coverage: Instead of a PTZ that only looks at one spot at a time, you get dedicated coverage of a 360 area.
Deterrent effect: It is hard for people to miss 4 cameras on a pole.
Drawbacks of CCTV Camera Clusters
However, there are also drawbacks:
Worse Angles: Because the cameras are all mounted on a single spot, the angles of incidents to people and cars may be worse than putting them at different locations aimed directly at key traffic flows.
Expensive product cost: 4 cameras with 4 outdoor housings, VMS licenses, etc. is costly. Perhaps a panoramic would be better in such a location, it certainly would be much less expensive.
Aesthetic problems: It is so overt that it could make people uncomfortable or unsafe.